Research

Oxidative stress is increased in critically ill patients according to antioxidant vitamins intake, independent of severity: a cohort study

Jimena Abilés¹ , Antonio Pérez de la Cruz¹, José Castaño², Manuel Rodríguez-Elvira², Eduardo Aguayo², Rosario Moreno-Torres¹, Juan Llopis³, Pilar Aranda³, Sandro Argüelles⁴, Antonio Ayala⁴, Alberto Machado de la Quintana⁴ and Elena Maria Planells³

¹Nutrition and Dietary Unit, Virgen de las Nieves Hospital, Fuerzas Armadas Avenue, 18014 Granada, Spain

²Critical Care Unit, Virgen de las Nieves Hospital, Fuerzas Armadas Avenue, 18014 Granada, Spain

³Institute of Nutrition, Physiology Department, University of Granada, Campus de la Cartuja, 18071 Granada, Spain

⁴Biochemistry Department, University of Seville, Profesor García Gonzales street, 41012 Seville, Spain

author email corresponding author email

Critical Care 2006, 10:R146doi:10.1186/cc5068

Published:	13 October 2006

Abstract

Introduction

Critically ill patients suffer from oxidative stress caused by reactive oxygen species (ROS) and reactive nitrogen species (RNS). Although ROS/RNS are constantly produced under normal circumstances, critical illness can drastically increase their production. These patients have reduced plasma and intracellular levels of antioxidants and free electron scavengers or cofactors, and decreased activity of the enzymatic system involved in ROS detoxification. The pro-oxidant/antioxidant balance is of functional relevance during critical illness because it is involved in the pathogenesis of multiple organ failure. In this study the objective was to evaluate the relation between oxidative stress in critically ill patients and antioxidant vitamin intake and severity of illness.

Methods

Spectrophotometry was used to measure in plasma the total antioxidant capacity and levels of lipid peroxide, carbonyl group, total protein, bilirubin and uric acid at two time points: at intensive care unit (ICU) admission and on day seven. Daily diet records were kept and compliance with recommended dietary allowance (RDA) of antioxidant vitamins (A, C and E) was assessed.

Results

Between admission and day seven in the ICU, significant increases in lipid peroxide and carbonyl group were associated with decreased antioxidant capacity and greater deterioration in Sequential Organ Failure Assessment score. There was significantly greater worsening in oxidative stress parameters in patients who received antioxidant vitamins at below 66% of RDA than in those who received antioxidant vitamins at above 66% of RDA. An antioxidant vitamin intake from 66% to 100% of RDA reduced the risk for worsening oxidative stress by 94% (ods ratio 0.06, 95% confidence interval 0.010 to 0.39), regardless of change in severity of illness (Sequential Organ Failure Assessment score).

Conclusion

The critical condition of patients admitted to the ICU is associated with worsening oxidative stress. Intake of antioxidant vitamins below 66% of RDA and alteration in endogenous levels of substances with antioxidant capacity are related to redox imbalance in critical ill patients. Therefore, intake of antioxidant vitamins should be carefully monitored so that it is as close as possible to RDA.